Welcome to the third annual ESPN.com ranking of the top 100 prospects in baseball. The No. 1 prospect for 2008, Evan Longoria, ended up winning the American League Rookie of the Year Award, and last year's No. 1 prospect, Matt Wieters, has already been inducted into Cooperstown, according to MattWietersFacts.com.

The rankings are limited to players who still have rookie eligibility; that means they have yet to exceed 130 at-bats or 50 innings pitched in the majors and have not yet spent 45 days on the active roster of a major league club, excluding call-ups during the roster expansion period after Sept. 1. Only players who have signed professional contracts are eligible. When ranking players, I consider scouting reports on players -- usually my own, supplementing with conversations with other scouts and front-office executives as needed -- as well as performance, adjusted for age and context. I've made one adjustment in my ranking philosophy, favoring higher-upside prospects over lower-ceiling prospects who are closer to the majors. This better reflects how these players are valued now by front offices and scouting departments and gives me a chance to deliver more information on prospects whose names or scouting reports might be new to you.

I've included last year's rank for players who appeared in the top 100 last offseason. An "ineligible" player (IE) was still an amateur at this time last January, whereas an "unranked" player (UR) was eligible but didn't make the cut.